In the medical field, hitherto, there has widely been used a method whereby aggregation patterns of blood particles, latex particles, carbon particles, and the like are discriminated and various components (for instance, a blood type, various antibodies, various proteins, and the like) in the blood, viruses, and the like are detected and analyzed. As such a discriminating method of the aggregation patterns, the microtiter method is relatively frequently used.
In the discrimination regarding the aggregation patterns, the presence or absence of aggregation is synthetically discriminated by a method whereby a distribution of particles in a well (i.e. reactive vessel) is detected as an area of the portions whose luminances are equal to or less than a predetermined luminance or is compared with a standard pattern or a standard non-aggregation pattern or, further, a method whereby a continuous step dilution series of a specimen sample is formed, or the like. For instance, a shadow of FIG. 5(a) is determined to be negative and a shadow of FIG. 5(b) is decided to be positive.
FIG. 6 shows a conventional example wherein an aggregation pattern P in a well (reactive vessel) 100A formed on a microplate 100 is optically projected onto a CCD line sensor 101. Either line sensor 101 or microplate 100 is sequentially finely moved relative to the other in a direction perpendicular to the paper surface, thereby obtaining a (light and dark) two-dimensional image of the aggregation pattern P. In FIG. 6, reference numeral 102 denotes a light source, 103 indicates an image forming lens, and 104 a lens holder.
On the other hand, an actual microplate 100 having a plurality of concave reactive vessel portions (wells) 100A is shown in FIG. 7. For instance, a positive or negative aggregation pattern as shown in FIG. 5 is produced in each of the wells due to the antigen and antibody reaction between the components in the blood and the reagent.
However, when setting the microplate into the apparatus main body, the setting position is mechanically preset. Therefore, if a deformation of a frame body of the apparatus main body, or a positional deviation of a movement start position (origin) of driving means for moving the photosensitive means or the like occurs, there occurs an inaccuracy in that the position of a scan start point of the CCD line sensor for the aggregation pattern is deviated. Since such a positional deviation of the scan start point of the CCD line sensor is not constant in every device produced, if such a state is left for a long time, the reliability of the measurement data deteriorates.
It is thus an object of the invention to improve upon the conventional example mentioned above and to provide an aggregation pattern detecting apparatus which can immediately set a measurement starting position for an aggregation pattern, thereby improving the reliability of the whole apparatus.
The invention comprises a microplate having a plurality of reactive vessel portions in which aggregation patterns are formed, a light source arranged above the microplate, and photosensitive means which is arranged below the microplate and has a CCD (charge coupled device) line sensor. The invention also comprises: an apparatus main body to fix the microplate; a moving frame body which is movably supported on the apparatus main body and integratedly moves the light source and the photosensitive means in a predetermined direction; driving means for intermittently or continuously setting a moving amount of the moving frame body; and a main control section to control the operation of the driving means. A reference plate having a plurality of through holes corresponding to the reactive vessels on the microplate is provided separately from the microplate. The reference plate is arranged at the attaching position of the microplate, and thereafter distances S.sub.0 from a start point of the driving means to the through holes of the reference plate are measured and stored into the main control section. On the basis of the stored distances S.sub.0, the main control section executes predetermined arithmetic operations and detects measurement starting positions for the reactive vessel portions on the microplate by the driving means and determines operation start timings of the CCD sensor. With the above construction, the above object is accomplished.